1. Field of the Invention
The present invention relates to a polycrystalline silicon layer, a flat panel display using the same, and methods of fabricating the same, and more particularly, the present invention relates to a polycrystalline silicon layer, a flat panel display using the same, and methods of fabricating the same in which when an amorphous silicon layer is crystallized into the polycrystalline silicon layer, a seed region is crystallized using a Super Grain Silicon (SGS) crystallization technique to have an area of 400 μm2 or more, the crystallinity of the seed region is enhanced to become a crystallization region, the crystallization region is patterned into a semiconductor layer, and the flat panel display is manufactured using the semiconductor layer.
2. Description of the Related Art
A thin film transistor used in a flat panel display, such as an organic electroluminescent device, is manufactured by depositing an amorphous silicon layer on a transparent substrate, such as a glass or Si substrate, dehydrogenating the amorphous silicon layer, ion-implanting impurities for forming a channel, crystallizing the amorphous silicon layer to form a polycrystalline silicon layer, and then patterning the polycrystalline silicon layer to fabricate a semiconductor layer.
Methods of crystallizing the amorphous silicon layer into a polycrystalline silicon layer include Solid Phase Crystallization (SPC), Excimer Laser Crystallization (ELC), Metal Induced Crystallization (MIC), and Metal Induced Lateral Crystallization (MILC). SPC is a method of annealing an amorphous silicon layer for several to several tens of hours at a temperature of about 700° C. or less, which is a transition temperature of glass used as a substrate of a display device employing a thin film transistor. ELC is a method of crystallizing a silicon layer by irradiating it with an excimer laser and locally heating it to a high temperature for a very short time, and MIC is a method of using phase transfer induction from amorphous silicon to polysilicon by contacting the amorphous silicon layer with metals, such as Ni, Pd, Au and Al, or implanting such metals into the amorphous silicon layer. MILC involves a technique of inducing sequential crystallization of silicon by lateral diffusion of silicide formed by reacting metal with the silicon.
However, polycrystalline silicon layers crystallized by these methods are non-uniform with respect to thin film transistor characteristics, such as threshold voltage and off-characteristics, due to non-uniform grain size and irregular distribution of grain boundaries.